Add get and getRef functions in IP to access and modify internal state variables

...inearSolver/internalPoints/ipElecMagGenericThermoMech.cpp

NonLinearSolver/internalPoints/ipElecMagGenericThermoMech.h

NonLinearSolver/internalPoints/ipElecMagInductor.cpp

NonLinearSolver/internalPoints/ipElecMagInductor.h

NonLinearSolver/internalPoints/ipGenericTM.cpp

NonLinearSolver/internalPoints/ipGenericTM.h

NonLinearSolver/internalPoints/ipLinearElecMagInductor.cpp

NonLinearSolver/internalPoints/ipLinearElecMagInductor.h

NonLinearSolver/internalPoints/ipLinearElecMagTherMech.cpp

NonLinearSolver/internalPoints/ipLinearElecMagTherMech.h

NonLinearSolver/internalPoints/ipLinearElecTherMech.cpp

NonLinearSolver/internalPoints/ipLinearElecTherMech.h

NonLinearSolver/internalPoints/ipLinearThermoMechanics.cpp

NonLinearSolver/internalPoints/ipLinearThermoMechanics.h

NonLinearSolver/materialLaw/mlawElecMagGenericThermoMech.cpp

dG3D/src/dG3DIPVariable.cpp

dG3D/src/dG3DIPVariable.h